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A DISSERTATION Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Doctor of Philosophy, Major: Electrical Engineering, Under the Supervision of Professor Natale Ianno. Lincoln, Nebraska: December, 2015

Copyright (c) 2015 Jinya Pu

Abstract

Room Temperature Vulcanized (RTV) silicone and compounds are widely used in outer-space for bonding or potting spacecraft components. In geosynchronous equatorial orbit (GEO), the silicone may outgas species which can condense on optically sensitive surfaces and degrade their performance, therefore shortening the lifetime of spacecraft. In low-earth-orbit (LEO), the silicone rubber is subject to an energetic and corrosive environment. Atomic oxygen (AO) and ultraviolet radiation can cause abrasion and degradation of the silicone rubber, cause changes in existing condensed VCM films and affect the properties of VCM films condensing in this atmosphere. Experiments were performed to simulate GEO conditions. In this work, the outgassed effluent of RTV566 silicone condensed at three different temperatures.The VCM films were analyzed by an \textit{in-situ} quartz crystal microbalance (QCM) and spectroscopic ellipsometry (SE). A self-consistent analysis approach employing the QCM and SE data has been developed to link the physical and optical properties of the condensed VCM films. It has been shown that at 120K, the VCM film contained ice, while at 150 K and 180 K, the films condense via island nucleation. Experiments were performed to simulate LEO conditions. In this work, an electron cyclotron resonance (ECR) based system was utilized to create atomic oxygen. First, VCM films were deposited in a GEO simulation chamber, then these GEO films were transferred into the ECR system for the AO exposure. Second, the AO exposure and deposition of films occurred simultaneously to produce LEO films for the first time. The results showed that the AO exposed GEO films are optically different than the LEO simulated films.